diff --git a/manifest/Makefile b/manifest/Makefile
index 13aa0c82dbdc7e8a16408dd128513c0dc947cf0f..71112eb09b41bf21af1ea72746cd1ca363c1180e 100644
--- a/manifest/Makefile
+++ b/manifest/Makefile
@@ -40,7 +40,7 @@ _build/%: %
 
 manifest: $(foreach file, $(SOURCE), _build/$(file))
 	ocamlc -bin-annot -g -w @1..3@5..28@30..39@43@46..47@49..57@61..62 \
-		-I _build str.cma $^ -o manifest
+		-I _build -I +str str.cma $^ -o manifest
 
 # Running 'make -C manifest l1-deps.svg' produces
 # the dependency graph of the main Layer 1 executables